Veritas Volume Manager 4.1 Administrator's Guide (HP-UX 11i v3, February 2007)

Creating a Volume with a Version 0 DCO Volume

210 VERITAS Volume Manager Administrator’s Guide

Creating a Volume with a Version 0 DCO Volume

If a data change object (DCO) and DCO volume are associated with a volume, this allows

Persistent FastResync to be used with the volume. (See “How Persistent FastResync

Works with Snapshots” on page 53 for details of how Persistent FastResync performs fast

resynchronization of snapshot mirrors when they are returned to their original volume.)

Note The procedure described in this section creates a volume with a data change object

(DCO) and DCO volume that has a version 0 layout as introduced in VxVM 3.2. The

version 0 layout supports traditional (third-mirror) snapshots, but not full-sized

instant snapshots, space-optimized instant snapshots nor DRL configured within

the DCO volume. See “Version 0 DCO Vol ume L ayou t” on page 51 and “Vers ion 20

DCO Volume Layout” on page 51 for a description of the differences between the

old and new DCO volume layouts.

For details of how to configure a volume with a version 20 DCO and DCO volume,

see “Creating a Volume with a Version 20 DCO Volume” on page 212. This is the

preferred and recommended method.

See “Determining the DCO Version Number” on page 238 for details of how to

determine the version number of a volume’s DCO.

To perform fast resynchronization of mirrors after a system crash or reboot, you must also

enable dirty region logging (DRL) on a mirrored volume. To add a DCO object and DCO

volume to a volume on which DRL logging is enabled, follow the procedure described in

“Adding a Version 0 DCO and DCO Volume” on page 307.

Note You need a VERITAS FlashSnap

or FastResync license to use the Persistent

FastResync feature. Even if you do not have a license, you can configure a DCO

object and DCO volume so that snap objects are associated with the original and

snapshot volumes. For more information about snap objects, see “How Persistent

FastResync Works with Snapshots” on page 53.

To create a volume with an attached version 0 DCO object and volume, use the following

procedure:

1. Ensure that the disk group has been upgraded to version 90. Use the following

command to check the version of a disk group:

# vxdg list diskgroup

To upgrade a disk group to version 90, use the following command:

# vxdg -T 90 upgrade diskgroup

For more information, see “Upgrading a Disk Group” on page 169.